Blynk controlled Power socket suddenly turns off/ on randomly it looses connection to the blynk servers

I made myself a Blynk controlled Power socket, with an array of 8 relays so I can switch connected stuff on an off. in this case I controll the power to my 3D Printers. It worked perfectly fine for years.
Once the ESP8266 lost connection to the internet my 3D printers remained on and could finish their print job, so that was never a real problem other then once the print was done to restart my setup. But lately it behaves very weird. whenever I loose connection to the blink servers minutes or hours later my setup randomly switches on and off my printers, it was never like that before. Its like someone else is controlling my setup?! Its all on still running on blynk legacy and so far never encountered a problem until recently?! Could this be a security Issue?

It could be lots of things - hardware, power supply, router etc etc.

But, it will all stop working on 31st December when the Blynk cloud servers are turned off anyway, so probably time to re-visit your project and refresh things a little.

What type of board and connection type are you using?


1 Like

I am using a Node MCU board, a level shifter and a typical Arduino relay board with 8 relays of them, each connected to a power socket.2x 5 volt power supplies, one for the relay board and a separate one for the node mcu and level shifter.

Not all of the GPIOs are usable. some GPIOs are not recommended for use, and others have specific functions.
You can check this article

The nodemcu doesn’t have enough safe pins to control 8ch relay module, so I’d suggest using esp32 instead. it has more GPIO pins.


The level shifter shouldn’t be necessary, but as @John93 has said, you can’t reliably operate 8 relays from a NodeMCU without a multiplexor device.

You should probably take a look at this: